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Reacti ting ng flow modeling ng and applica cati tions ns in STAR-CCM+ Yongzhe gzhe Zhang, ng, CD-adapco pco LES: : Scaled d Combust ustor Bet etter er flow and mixing ng accurac racy Results lts in bett etter er predic


  1. Reacti ting ng flow modeling ng and applica cati tions ns in STAR-CCM+ Yongzhe gzhe Zhang, ng, CD-adapco pco

  2. LES: : Scaled d Combust ustor Bet etter er flow and mixing ng accurac racy Results lts in bett etter er predic iction ion with th PVM combus bustion tion model dels ~32.7 .7 million ion cells ls Δ t = 1x10-6 s

  3. LES Flare: : Impr mproved d predi dicti ction n of combus usti tion n effici ciency ncy PVM model el ~15 million lion cells ls Δ t = 5x10-5 5 s A Validation of Flare Combustion Efficiency Predictions from Large Eddy Simulations. Anchal Jatale, Philip J. Smith, Jeremy N. Thornock, Sean T Smith, Michal Hradisky. University of Utah. Combustion and Flame.

  4. Applicat ication ion trend More Large ge Eddy y Simulatio mulation n (LES) ES) – Better prediction of instantaneous flow characteristics and turbulence structures – Computationally expensive Include ude Detailed d Chemi mistr try – Better prediction of autoignition and emissions (CO/NOx) – Models • Complex Chemistry model • Tabulated Chemistry model

  5. Complex Chemistry Model Transport equation of chemical species Nonlinear, stiff ordinary differential equations (ODEs) Effici icient t ODE solve ver Analyti lytica cal l Jacob cobia ian Load bala lancin cing for parall llel l compu mputi ting Computa tati tional Chemistry mistry reducti ction : Offli line (DRG) Cost Storage/Re /Retrie trieva val l Sch cheme me(IS ISAT AT) Equil ilib ibriu ium m Time Scale le (Init itia iali liza zati tion) Dars-CFD FD Turbule lence ce- Eddy y Dissip ipati tion Conce cept (EDC) chemi mistry stry Interactio ction

  6. Equi quili libri brium um Time e Scale e Model (EqTS TSM) ‏ Motiva vati tion – A better initial condition can greatly accelerate DARS-CFD Model – The model assumes the species composition to relax towards the local chemical equilibrium at a characteristic time scale determined based on the local flow and chemistry time scales – Quickly provides an reasonable initial condition to DARS-CFD – Results similar to PPDF equilibrium, but more flexible: • no stream limitation/no precomputed table needed/easier to set up – Can be used as a standalone model to obtain a quick approximate solution

  7. Tabula ulated ed Chemis mistr try y Model Motiva vati tion – Detailed chemistry is important to predict autoignition and emissions (CO/NOx) – Computationally expensive to include a full set of species Tabulated d Detailed d Chemi mistr stry y for turb rbul ulent nt combustion ustion – Precompute chemistry table and retrieve during CFD computation • Can use large mechanism – Dimension reduction to chemistry – Consider turbulence-chemistry interactions. Existi ting ng models – PPDF with equilibrium – PPDF with laminar flamelets – PVM (Progress variable model) – FGM (Flamelet Generated Manifold)

  8. FGM combus bustion tion model Simi milar r to the existi sting ng PVM model: – A tabulated detailed chemistry model – A progress variable is used to bridge the CFD side and the table Impr mproveme ment nts s comp mpared d to the exist sting ng PVM model – Table is from flamelet manifold • A turbulent flame is an ensemble of laminar flamelets – Option of using progress variable variance • Presumed Beta PDF in progress variable space – Option of considering heat loss ratio – Flexible progress variable definition • Chemical enthalpy – Sum over all species • Species weights – Defaults: YCO+YCO2

  9. FGM table le genera eratio tion in DARS-BASI ASIC Generated table can directly be loaded into STAR-CCM+ for • 9 further construction

  10. Validation tion with h IFRF F glass s furnace nace Heat loss effect is important

  11. Latest t model l additions tions (v 9.04 04-10.0 0.04) 4) Includ lude e det etailed ed chemist mistry y with an affor ordabl able e computation putational al cost – Equilibrium Time Scale – Flamelet Generated Manifold (FGM) Cope e with h more e comple plex conf nfigurat igurations ions – Inert stream – Reacting channels Expand nd appli licati cation on coverages erages – Polymerization – Surface chemistry with multiple sites and open sites 11

  12. Reacti tion n models s in STAR-CCM+ Non-Premixe Premixed Combust stio ion Premixe mixed Combusti stion Multi ti-co compo mponent t Gas Parti tiall lly-Pre Premixe mixed Combust stio ion Reactio Emissio ssion Models s (Soot/ t/NO NOx/CO) x/CO) ction Models Eddy y Conta tact ct Model l (ECM) Multi ti-co compo mponent t Liquid id Polyme ymeriza izati tion Parti ticle cle Reactio ction ls Lagrangia ian Multi tiphase se Coal l combu mbusti stion Eule leria ian Multi tiphase se Interphase se Reactio ction Surfa face ce Chemistry mistry Reacti cting Channel

  13. Latest t model l additions tions (v 9.04 04-10.0 0.04) Includ lude e det etailed ed chemist mistry y with an affor ordabl able e computation putational al cost – Equilibrium Time Scale – Flamelet Generated Manifold (FGM) Cope e with h more e comple plex conf nfigurat igurations ions – Inert stream – Reacting channels Expand nd appli licati cation on coverages erages – Polymerization – Surface chemistry with multiple sites and open sites 13

  14. Inert t stream eam for r PPDF combu mbust stion ion model el Motiva vati tion – To reduce the PPDF table size for complex configurations where one stream, or part of the stream, is inert (negligible reactivity and sole effect is for dilution) Inert t str tream m treatm tment nt – Only consider its dilution effects to the reacting mixture – Compared to take it as active • Smaller table size • Faster table generation • Faster interpolation Inert t strea tream m model – A transport equation for the mixture fraction solved for inert stream – Species mass fractions from reacting and inert streams – Temperature from local total enthalpy and mean species

  15. Reacti cting ng Channel nel Co-Si Simu mulation ation Applic ication ation Modelin eling of Proces ess side – Process heaters – Cracking furnaces – Steam reformers Modeling eling Challen llenges es – Firebox side has multiple burners – Process side has many tubes – Full 3-D modeling is computationally intensive Perform ormanc ance e Considerat ideration ions – Uniform heat distribution – Emissions 3-D vs 1-D – Conversion rate Comput mputationally Comput mputationally less s expensi sive expe pensi sive

  16. Reacti cting ng Channel nel Co-Si Simu mulation ation An elega gant nt way to fully ly couple le Firebo rebox side e and Proces ess side Gas-Pha Phase: e: [ FireB eBox Side] e] – 3-D, turbulent flow – Combustion models – Heat transfer Proces ess Side Side Reacti ting g Chann nnel: el: [Proc oces ess Side] de] – 1-D Plug Flow Reactor (PFR) – Inlet composition, temperature – Process-side reactions – No meshing, solving with STAR-CCM+ Burner er Couplin ling – Temperature is provided to the process side – Heat flux is returned back to firebox side

  17. Output put from om Co-simul simulation ation : Process ess Side Axial l distr trib ibution ution of Temperature, erature, Heat t Flux, , and Species ies convers ersions ions CH4 Mass Fraction H2 Mass Fraction

  18. Polymeri ymeriza zation tion Expand and our applica cati tion n coverage age Polym ymeriza rizati tion on Process cess – monomers are linked by chemical reactions to form long chains – starts with mixing a Monomer (M) and an Initiator (I) in a Solvent (S) – Steps involved: initiation/propagation/transfer/branching/termination – Final product is polymers of varying lengths and structure. Polym ymerizati zation on Moment nt Model for free radical cal polym ymerizati tion – Scalar Transport Equations for Moments are solved in STAR-CCM+: live/dead polymers – source terms of the above moment transport equations depend on the sub processes of polymerization. – Provide: total polymer concentrations, NACL/NAMW, WACL/WAMW, polydispersity index

  19. Industri ustrial-Sca Scale Stirred d Tank k Reactor – Styrene ne Polym ymerization zation Steady (Implicit Unsteady) • K-Epsilon Turbulence • Realizable K-Epsilon Two-Layer • Two -Layer All Y+ Wall Treatment • Multi-Component Liquid • Polymerization • Segregated Flow • Segregated Fluid Enthalpy • Three Dimensional • MRF, RBM • Polyd ydisp ispersit sity index

  20. Multi tiple ple sites s for surface ce chemi mistr try Chemical vapor deposition (CVD) reactor

  21. Open sites es for r surface ce chemi emistr stry Adsorption ption reacti tion n descr cripti tion – Atomic Site • AsH3(g)+Ga(s)->AsH3(s)+Ga(b) – Open Site • O(s)+AsH3(g)->AsH3(s) Open sites s treatm tment nt – Considered as a species – Contains no element (empty) – Named as OPEN in the CHEMKIN kinetics input file

  22. Application ication extens nsions ions Large ge Eddy Simul mulation ation (LES) S) with h det etailed ed chemist mistry – Gas turbine combustors – Burners, Furnaces and Incinerators – Fires High h speed ed flows ws – Scramjet – Rocket engine nozzles Multipha phase se react ctions ions – Coal reactors: Pulverized/Fluidized bed – Surface chemistry (SCR/CVD) Optimiz mizations tions – Chemistry – Combustor design

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